Die member

ABSTRACT

There is disclosed in this application a thread rolling die including a plurality of rib members secured together in abutting relationship. One longitudinal edge of each rib member includes a configuration which is operative to form a thread on a screw blank.

United States Patent [191 Wilson Oct. 7, 1975 [54] DIE MEMBER 1,232,876 7/1917 Wilcox 72/469 1 mm Charles Wilson, wmiamswwn, 513321333 31513 52223111111113: 11:11:31.75523 2,371,365 3/1945 Tomalis 72/469 [73] Assignee: Standard Pressed Steel Co.,

JenkintOWn, Primary Examiner-C. W. Lanham [22] Filed: Dec. 26, 1973 Assistant ExaminerRobert M. Rogers 21 Appl. No.: 428,113

[57] ABSTRACT [52] U.S. Cl 72/469; 72/88 There i dis lo ed in this application a thread rolling Clincluding a plurality of members ecured to- Fleld of a c 107 R gather in abutting relationship. One longitudinal edge of each rib member includes a configuration which is References Cited operative to form a thread on a screw blank.

UNITED STATES PATENTS 408,530 8/1889 Rogers 72/88 12 7 Draw Flgures IO l5 2o 22 6 24 Sheet 1 of 2 3,910,099

US. Patent 00:. 7,1975

FIG. I

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Sheet 2 0f 2 FIG. 6

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US. Patent Oct. 7,1975

urn in The most conventional thread rolling technique utilizes a plurality of spaced apart dies, either flat or circular, each including on their adjacent faces a plurality of rib like serrations whereby a screw blank rotated between the dies will be acted on by the serrations to cause the metal of the blank to flow and form a helical thread. Such a technique is widely used because it provides an efficient and economical method for producing externally threaded fasteners. However, because of the configuration of the dies and their method of manufacture, the type of thread configurations which can be economically formed are somewhat limited. Prior to this invention, it has been usual to machine one face of the die to provide the serrations which generally include a crest and a root joined by flanks, all of which are complementary to the thread to be formed on the screw blank. If special configurations are to be provided on the flanks or in the root of the die, secondary machining operations may be required which cannot easily be performed in these areas. Accordingly, the cost of the dies is relatively expensive and, therefore, certain thread forms cannot be economically pro* duced. Among these thread forms are those including special knurls on the flanks of the thread as disclosed in copending application Ser. No. 257,730 filed on. May 30, 1972, now abandoned, and refiled as continuation application Ser. No. 470,848 on May 17, 1972, or those including a deflection at the crest and root of the thread as disclosed in copending application Ser. No. 428,112 filed on Dec. 26, 1973.

Another problem with conventional dies involves the fact that when special thread configurations are to be formed, the serrations on the dies complementary to the special thread form are subjected to relatively: high working stresses which cause these specially formed serrations to wear out or break sooner than those areas of the die utilized to form conventional thread forms. Thus, resort has been made to the use of special inserts in the form of a smaller block of material on which a plurality of working faces or ribs including the specially formed serrations are provided and are placed in an opening in the die member which is formed with the conventional serrations. Thus, when the insert wears out it can be replaced without necessitating the replacement of the entire die member. However, because the insert includes a plurality of serrations, it too is limited in the special thread configurations which it can economically and efficiently form.

Accordingly, it is an object of this invention to provide a die member capable of rolling special thread configurations in an economical and efficient manner.

It is yet another object of this invention to provide a die member that is relatively simple and inexpensive to make.

These and other objects of this invention are accomplished by providing a plurality of elongated rib members each having an edge configuration for working a fastener blank and forming a thread thereon. The rib members are secured together in abutting relationship with the edge configurations facing the same direction to form a die. Thus, each rib member, before being secured together, may be easily worked along its flanks or root area which facilitates forming special configurations.

In one preferred embodiment of the invention, the rib members are located between two die members each having a plurality of serrations thereon and extend throughout the longitudinal extent of the die members.

In yet another embodiment. of the invention, the rib members are secured within an opening formed through the face of a die member having a plurality of serrations formed thereon.

For a better understanding of the invention, reference may be made to the following description of several preferred embodiments thereof, taken in conjunction with the Figures of the accompanying drawings, in which:

FIG. 1 is a perspective view of a die in accordance with this invention;

FIG. 2 is a front view of the die illustrated in FIG. 1; FIG. 3 is a top plan view of the die illustrated in FIG.

FIG. 4 is an end view of rib member utilized in dies according to this invention;

FIG. 5 is an end view of a plurality of rib members illustrated in FIG. 4 arranged in abutting relationship;

FIG. 6 is a front view of another embodiment of a die in accordance with this invention; and

FIG. 7 is a side view of the die illustrated in FIG. 6.

Referring to FIGS. 1 3, there is illustrated a thread roll die 10, that is, a die for rolling a thread configuration on a screw blank, in accordance with one embodiment of this invention. Die 10 comprises a first die member 12 and a second die member 14 each having a plurality of serrations extending across one face 15 thereof. Face 15, in plan, is generally shaped in the form of a trapezoid. Serrations 16 are in the form of ribs having generally inverted V-shape and extend across the entire longitudinal extent of die members 12 and 14 at an acute angle to the longitudinal axis thereof. Each rib includes a pair of flanks joined at their free end by a crest and separated from the adjacent rib by a root. Located in abutting relationship between die members 12 and 14 are a plurality of elongated rib members 18 each of which includes, along one edge, a working surface 19 generally similar to one of serrations 16 formed on the die members. Extending transverse to the longitudinal axis of the die members and the rib members are a plurality of holes 20 in which suitable fasteners 22 are placed to secure the die members and inserts together in abutting relationship. Fasteners 22 may take the form of socket head cap screws, set screws, spring pins, or any suitable combination thereof.

Extending from face 15 of each die member 12 and 14 is a generally straight longitudinal surface 24, a pair of transverse surfaces 26 extending at generally right angles to surface 24, and an inclined longitudinal surface 28 fonning an acute angle with the longitudinal axis of the die member. Eaclh surface 28 is generally parallel to serrations l6 and, accordingly, form the same acute angle with the longitudinal axis of the die member as the serrations. Of course, transverse surfaces 26 do not extend an equal distance from surface 24.

Referring to FIGS. 4 and 5., each rib member 18 includes longitudinal side walls 30 and a bottom wall 32 connecting one end of each side wall 30. At the other end of side walls 30 is a serration in the form of a rib 34 generally in the shape of an inverted V and including a pair of flanks 36 extending upwardly and inwardly from side walls 30 and connected by a crest 38. When rib members 18 are stacked with side walls 30 in abutting relationship as illustrated in FIG. 5, the ribs 34 form a plurality of serrations similar to those on face of die members 12 and 14. The intersection of side walls 30 and flanks 36 form a root corresponding generally to the root formed on die members 12 and 14 while crest 38 corresponds to the crests formed on the die members.

Thus, when a particular special configuration is to be formed on a portion of the thread formed on a fastener, each insert may be readily machined or otherwise deformed to provide the required configuration. For example, if the flank of the thread is to be knurled as disclosed in copending application Ser. No. 470,848 referred to above, flank 36 may be machined or otherwise worked to include the desired serration configuration; or, adjacent its crest, as disclosed in copending application Ser. No. 428,112, flank 36 on each rib member may be easily deformed, particularly adjacent side walls 30, to provide the required configuration.

It should be understood that dies 10 are used in pairs and are initially offset so that only a slight overlap of the dies is provided. Thereafter, the cylindrical shank of a fastener blank is inserted in between the overlapping portions of the dies which are then moved relative to each other so that the fastener blank is rotated against the serrations which cause the material of the blank to flow and form the thread configuration.

Referring now to FIGS. 6 and 7, there is illustrated another embodiment of a die in accordance with this invention. In this embodiment, die 40 is in the form of a generally rectangular die member 42 having a plurality of serrations 44 formed on one face thereof extending at an acute angle with respect to the longitudinal axis of the die member. Each serration is in the form of a rib having a generally inverted V-shape and includes a pair of flanks joined at their free end by a crest and separated from the adjacent rib by a root.

Formed adjacent one end of die member 42 is a rectangular opening 46 which extends through both faces of the die member. Opening 46 is formed by a pair of generally longitudinal walls 48 which extend at an acute angle to the longitudinal axis of the die member and which are generally parallel to the serrations 44 and by a pair of transverse walls 49 extending at right angles to the longitudinal walls. A plurality of inserts 18, similar to those illustrated in FIGS. 4 and 5 except that their length is substantially equal to that of longitudinal walls 48, are located in opening 46. A first opening 50 extending through the top longitudinal surface of die member 42, as illustrated in FIG. 6, terminates at the top longitudinal wall 48, as illustrated in FIG. 6, of rectangular opening 46 and is internally threaded to receive a set screw 52 which bears on side wall 30 of adjacent rib member 18 to retain the inserts therein. A second opening 54 extends through the transverse surface of die member 42 to transverse wall 49 of opening 46 and is also internally threaded to receive a set screw 56 to retain the inserts therein.

As clearly shown in FIG. 6, the surface of die member 42 extending between the right hand wall 49 of opening 46 and the right hand transverse surface of die member 42 is not formed with serrations, but is a flat planar surface. Therefore, in use, as the fastener blank passes beyond rib members 18 no further working of the thread formed on the blank occurs. In this way, any

special thread configuration formed by the rib members is not destroyed or altered by the serrations formed on the die member.

In view of the foregoing, it can be seen that dies for imparting a special thread configuration can be formed in an economical and efficient manner and that in use the dies are efficient in that the rib members may be readily replaced without necessitating the replacement of the entire die. In addition, it should be noted that the rib members may be easily adjusted by shimming to assure that the thread configuration is properly formed.

While in the foregoing, there has been described several preferred embodiments of the invention, it should be understood that various modifications may occur to those skilled in the art. For example, an entire die member may be formed by a plurality of rib members rigidly secured together in a suitable fashion or the inserts and die members could be circular to form circular thread roll dies. Thus, the scope of the invention will be set out in the appended claims.

I claim:

1. A die for rolling threads on a fastener blank including a plurality of individual rib members each separable from the other secured together in abutting relationship, each individual rib member having a single edge only, said edge having a working configuration thereupon for forming a thread on a fastener.

2. A die in accordance with claim 1 wherein said rib members are located between two die members in abutting relationship therewith, said die members having a working configuration for forming a thread on a fastener.

3. A die in accordance with claim 1 wherein said rib members are located in an opening formed in a die member having a working configuration on one face thereof for forming a thread on a fastener.

4. A die for rolling threads on a fastener blank including first and second die members each having a working configuration formed on one face thereof for producing a thread on the fastener blank and a plurality of individual members each separable from the other rigidly secured between said first and second die members, each individual rib member having a single edge only, said edge having a working configuration formed thereupon for producing a thread on the fastener blank.

5. A die in accordance with claim 4 wherein said working configuration on said first and second die members includes a plurality of ribs and wherein said working configuration on each of said rib members includes a rib.

6. A die in accordance with 'claim 4 wherein said first and second die members each include a longitudinal surface forming an acute angle with the longitudinal axis thereof and wherein each of said surfaces is adjacent an outer wall of one of said rib members.

7. A die for rolling threads on a fastener blank comprising a die member having a working configuration formed on one face thereof for producing a thread on the fastener blank, said die member having an opening formed through said one face, and a plurality of individual rib members each separable from the other rigidly secured in said opening, each individual rib member having a single edge only, said edge having a working configuration formed thereupon for producing a thread on the fastener blank.

the longitudinal axis of said die member.

1 1. A die in accordance with claim 7 wherein said rib members are secured in abutting relationship having their longitudinal axes parallel to each other.

12. A die in accordance with claim 4 wherein said rib members are secured in abutting relationship having their longitudinal axes parallel to each other. 

1. A die for rolling threads on a fastener blank including a plurality of individual rib members each separable from the other secured together in abutting relationship, each individual rib member having a single edge only, said edge having a working configuration thereupon for forming a thread on a fastener.
 2. A die in accordance with claim 1 wherein said rib members are located between two die members in abutting relationship therewith, said die members having a working configuration for forming a thread on a fastener.
 3. A die in accordance with claim 1 wherein said rib members are located in an opening formed in a die member having a working configuration on one face thereof for forming a thread on a fastener.
 4. A die for rolling threads on a fastener blank including first and second die members each having a working configuration formed on one face thereof for producing a thread on the fastener blank and a plurality of individual members each separable from the other rigidly secured between said first and second die members, each individual rib member having a single edge only, said edge having a working configuration formed thereupon for producing a thread on the fastener blank.
 5. A die in accordance with claim 4 wherein said working configuration on said first and second die members includes a plurality of ribs and wherein said working configuration on each of said rib members includes a rib.
 6. A die in accordance with claim 4 wherein said first and second die members each include a longitudinal surface forming an acute angle with the longitudinal axis thereof and wherein each of said surfaces is adjacent an outer wall of one of said rib members.
 7. A die for rolling threads on a fastener blank comprising a die member having a working configuration formed on one face thereof for producing a thread on the fastener blank, said die member having an opening formed through said one face, and a plurality of individual rib members each separable from the other rigidly secured in said opening, each individual rib member having a single edge only, said edge having a working configuration formed thereupon for producing a thread on the fastener blank.
 8. A die in accordance with claim 7 wherein said working configuration on said die member includes a plurality of ribs and wherein said working configuration on each of said rib members includes a rib.
 9. A die in accordance with claim 7 wherein said opening is rectangular.
 10. A die in accordance with claim 7 wherein the longitudinal walls of said opening form an acute angle with the longitudinal axis of said die member.
 11. A die in accordance with claim 7 wherein said rib members are secured in abutting relationship having their longitudinal axes parallel to each other.
 12. A die in accordance with claim 4 wherein said rib members are secured in abutting relationship having their longitudinal axes parallel to each other. 